We can all watch the waters of Hood CanalAugust 24th, 2009 by cdunagan
It’s time to start watching Hood Canal’s dissolved oxygen levels to see if anything bad may happen.
As I explained in a story in today’s Kitsap Sun, the canal had record-high levels of dissolved oxygen early in the year. But now the rate of decline is surprisingly rapid, and nobody can say how low it will go.
I am grateful to the Hood Canal Dissolved Oxygen Program for making it easy to follow changes in Hood Canal’s dissolved oxygen levels. You can take a look at four places in Hood Canal by going to the Web site that contains updated data from four monitoring buoys, known as ORCA (Oceanic Remote Chemical-optical Analyzer) buoys. Besides oxygen, the buoys monitor for temperature, salinity, chlorophyll and currents.
Do you want to see the steep line I was writing about? Click here for a graph called the “Average Dissolved Oxygen at Depth.” Those big pink boxes are this year’s average levels for Hood Canal. We need to watch to see where the next point on the graph will show up.
If you want to predict a fish kill, it is best to look at the data from the Hoodsport buoy. The fourth graph (first tourquise line) shows the concentration of oxygen at various depths. The closer to the dotted line it gets in shallow water, the greater the risk.
Another revealing graph is a time series that looks back over the past few years. When the shades of blue go all the way up to the surface in the second and third charts, the fish will move away if they can. If it happens fast, they may not get away.
Following a massive fish kill in September 2006, researchers went back to the time series and compiled an animation that shows how south winds blew away the surface waters in southern Hood Canal. That forced low-oxygen water up from the deep, and fish were unable to locate the higher-oxygen water that was actually below them for a while.
I’m trying to find this animation, and I’ll put the link here if and when I locate it. Meanwhile, here’s a little more detail provided in a report by Jan Newton (PDF 1.7 mb), who heads the scientific arm of the Hood Canal Dissolved Oxygen Program.